1. Field of the Invention
The present invention is concerned with improved valve structure especially adapted for selective closure of relatively large conduits or pipes. More particularly, it is concerned with such a valve structure which, in preferred forms, includes a hydraulic feature for enhancing the operability of the valve and permitting the same to be safely used in high pressure lines. Although the valve structure of the present invention has many possible uses, it is particularly adapted for employment in large scale commercial oil shale recovery units of the type employing the methods described in U.S. Pat. No. 4,088,562.
2. Description of the Prior Art
While a wide variety of valves are available for use in conjunction with lines of relatively small diameter, a completely different situation exists with respect to large diameter conduits and the like (on the order of twelve inches in diameter and more). In such cases valves are simply not readily available. Moreover, while such valves can be engineered and manufactured on the basis of a special order, the cost of the resultant valves is prohibitive.
The above factors are especially significant in connection with valves designed for selective opening and closing of conduits or the like carrying materials under pressure. In such cases it is difficult if not impossible to obtain valve performance guarantees, regardless of the price paid for the valves.
U.S. Pat. No. 4,088,562 describes a process for the recovery of hydrocarbons from oil shale. This process is a major breakthrough in the art, and engineering studies to date have indicated that it may be of significant help in alleviating the present energy crisis. However, in order to be commercially viable, the process must be operated using gaseous and solid material conduits of relatively large diameter (at present lines of up to forty-two inches in diameter are contemplated). Furthermore, at various points along these conduits, it is necessary to provide a valving function. Hence, the problems outlined above are particularly acute in connection with commercial-scale development of the process described in U.S. Pat. No. 4,088,562.